Soundhead



March 3., 1938. F ',J LOQMIS ET AL 2,109,451

SOUNDHEAD Original Filed Oct. 14, 1952 5 Sheets-Sheet 2 ATTORNEY- March 1, 1938.,

F. J. LOOMIS ET AL SOUNDHEAD Original Filed Oct. 14, 1932 3 Sheets-Sheet 3 INVENTOR F650 00405 544M005 11/. EEY/VOADJ ATTORNEY Patented Mar. 1, 1938 UNlTED STATES PATENT OFFICE SOUNDHEAD Fred J. Loomis, Haddonfield, N. J., and, Ellwood W. Reynolds, Drexel Hill, Pa., assignors to Radio Corporation of America, a corporation of Delaware Original application October 14, 1932, Serial No.

637,852, now Patent No. 2,019,147, dated October 29, 1935. Divided and this application June 26, 1935, Serial No. 28,444

; 4 Claims.

i talking picture art to provide a sound reproducing mechanism commonly known as a soundhead which is adapted for attachment to a motion picture projector and which is provided with a drive mechanism common to both the soundhead .and the projector so that a single film carryin both the picture and sound records can'be run consecutively through the two instrumentalities and sound can be reproduced from the film in oaxact synchronism with the picture projected from the same film.

The soundhead ordinarily includes an exciter lamp, an optical system and a photoelectric cell, although any other desirable form of sound takeoff may be used. The sound record moving mech- ,25 anism may be mounted inside or exterior to the soundhead. Considerable difiiculty has heretofore been encountered in the past due to the necessity for moving the film at an absolutely :uniform speed past the sound reproduction point,

:30 the production of such uniform movement being rendered diflicult because of the necessity of moving the film by means of sprockets cooperating with the sprocket holes therein, and because of irregularities in the operation of the driving 35 mechanism and its attendant gearing.

One object of the invention is the production of a soundhead which is adapted to cooperate with the standard types of motion picture apparatus and which is capable of such an extreme- 40 1y accurate movement of the film that a high degree of fidelity of the reproduced sound is realized.

Another object of the invention is the production of such a soundhead having greatest possible simplicity and lowest production cost,

Another object of the invention is the production of a sound head having a minimum number of moving parts.

Another object of the invention is the production of a soundhead which will permit large 50 manufacturing tolerances and at the same time produce a device having an extremely high degree of precision.

7 Another object of the invention is to provide a roller which will firmly hold the film in contact with the supporting drum at the reproduction point and guide it in a straight line laterally as it passes around the drum- Another object of the invention is to provide a guide roller which will laterally guide any given standard width of film regardless of the shrinkage thereof.

Another object of the invention is to provide a'guicle roller whose'frictional resistance to the film roller is small and whose variations to the I resistance are negligible whereby it affects to the' least possible extent the motion of the film drum.

Another object of the invention is to provide a lamp socket which will gently yetpositively hold the exciter lamp in proper alignment with the optical system.

Another object of the invention is toprovidc a lamp socket which can be instantly and easily removed or replaced in exact pos ti 1 t machine, thus allowing a burnt out exciter lamp to be instantly replaced by a new, one without requiring readjustment of the optical system.

Another object of the invention is to provide a lamp socket having mechanical characteristics which give it sufficient flexibility to prevent microphonic noises fromthe lamp, and at the same time sufiicient stiffness to hold the filament in correct position.

Another object of the invention is to provide an extremely simple and dependable film stripper.

Another object of the invention is to provide an improved pad roller for retaining the film upon the driving sprockets which is held definitely in position but Which is easily adjustable.

Another object of the invention is to provide a soundhead which will magnetically and electrostatically shield within itself the transformer used in conjunction with the photoelectric cell.

Another object of the invention is to provide a soundhead wherein the driving motor is built into the soundhead.

Another object of the invention is to provide a soundhead with the motor built thereinto with means for preventing stray magnetic fields and induced currents from the motor from permeating the soundhead.

Another object of the invention is to provide means for manually actuating the driving mechanism for purposes of adjustment, etc.

Another object of the invention is the provision of a pressure roller which will hold the film upon i system and the photocell.

Pressure roller It is necessary, in a device of the class described,

that the pressure roller indicated generally at 10 shall hold the film firmly against the filmdrum without slippage; that it rotate so freely as to avoid any interference with the operation of the drum; and that it guide the film laterally to maintain it exactly in position between the optical This portion of the device is shown in Figs. 1 to 3 inclusive.

' 'The roller surface I-OIJ is formed from a line grade of felt, and after being placed upon the combined spindleand clamping ring IOI is fastened rigidly thereupon bythe member I02 and "thereafter ground to'an, accurate circular form. -The me'mber lI-is'mounted upon a shaft I03 which extends entirely through the rotating portionslof the unit. 1 This shaft is carried in ball- *-bearings I04 and I which are mounted in a bracket hereinafter. described and protected by the collar members I06. Mounted firmly upon the shaft and abutting against the collar thereof is the guide member I01 which serves to guide the edge-of the film adjacent the soundtrack. The

- member I01 is separated from the adjacent ballbearing I04 bythe spacer member I08 which, with the assistance of the nut I09, holds the member I01-firmly against the shoulderon the shaft I03.

Themember IOI has fitted firmly thereupon a member -I I0 which'correspondls in general appearancc and function to the member I01, but the entire unit comprising the members I00, I01, I02, and I I 0 is slidable longitudinally on the shaft I 03 -and-is pressed toward the member I01 by the 1.

spring I II. The springl I I is fixed in position by *the shaft I03and is held thereagainstby the nut bracket member the collar I I2 which fits against the shoulder on II3 and-the inner ring of the ball-bearing I05. The spacing" of the members I01 and H0 is so chosen'th'at they will be slightly separated when a film of the minimum usable width is between them,"and'will of course be separated a greater distance by wider film. Due to the long bearing of the member IOI upon the shaft I03, the members I01-"and I I0 will always remain in exact parallelism, while the entire unit will rotate freely upon the ball-bearings I03 and I05.

The bearings I04 and I05 are supported in the bracket member I I5 which has the ring members H6 and H1 formed integral therewith. This bracket member is pivoted. at- H8 in a second 9. This pivoted joint, as shown in Figs. 8 and 9, is capable of only a very slight movement and serves to permit a slight vertical movement of the roller I00 in engaging the film upon the drum 50 The drum I 00 is I maintainedina firmbutyieldin engagement with the drum 50 by means of the spring I and the ball I20 shown in Fig. 1, in which figure they urge the bracket II 5 toward the right. I

'.The bracket H9 is mounted upon thepin I2I which is a press fit in the center plate of the soundhead due to'the shaping of the end I22 to fit an appropriately diametered hole in the center plate, in order that the pin I2I may be maintained accurately perpendicular to the said center plate without'thc inaccuracies ordinarily resulting from the tapping of a hole, or the threading of the end of the pin to fit into the tapped hole. The collar I23 fits snugly against the center plate, and against this collar bears the spring I24 which fits, as shown, into a recess in the member I I9 and thrusts the member I I 9 toward the outer end of the pin and against the member I25. The member I25 is threaded upon the outer end of the pin I2I so that it may be adjusted longitudinally thereon, is split and provided with a lock-screw I26 as shown. Lateral adjustment of the side guides I01 and II 0 relative to the roller 50 is accomplished by loosening the screw I26 and rotating the member I25 until the guides I01 and I I0 arein the proper positions when the member I25 is again locked bytightening the screw I26.

It is, of course, necessary to lock the pressure roller in operative position against the roller 50,

and to remove it fromthat position. Locking is accomplished by-means of the bolt I21 which is retained by anappropriate aperture in the center place, or by anadjustable plate secured thereupon. The bolt I21'is urged toward the center plate by the spring 128 and may be pulled outwardly by the knob I29. A thumb piece I is also provided. To open'the pressure roller the knob I29 is pulled outwardly, whereby the bolt I21 is removed. from its aperture,. and the pressure roller ispermitted to drop back, while to'close it into operating position the assembly is merely rotated by pressure of the member I30 until the bolt I21 snaps into the appropriate aperture, when the entire unit is locked in operating position. In operating positionthe roller is raised slightly-against the. pressure of the spring I20, which then maintains it in contact with the film upon the film drum. 7

- Exciter lamp socket The construction of the exciter lamp socket shown in detail in Figs. 4 and 5.

It is necessary, in photophonographic apparatus, that the exciter lamp be held rigidly in position, .thatit be adjustable vertically to align. it with the optical system, that it be provided with adequate and non-microphoniccontacts, that it beheld firmly against rotation during vertical adjustment, and that it be instantly replaceable by another pre-adjusted lamp. We have attained.

all these results by the construction shown.

A base plate-200 of insulating material is provided, which is attached to the center plate of the soundheadp Projectingfrom this base-plate are two round pins 20I and 202 provided with collars,

aperture extending therethrough adapted to co'- A block of insulating operate with the pin 20I. material 201 is attached to the bottom of the member 206 and is provided with a groove at its bottom adapted to cooperate with thepin 202. It will be apparent from Fig. 5 that substantially the entire weight of the unit lies to one side of the vertical plane of the pins 20I, 202 and the insulating block 201 is, thereby pressed firmly against therod 202. A contact spring 208 carried by the block 201 and presses firmly against the opposite side of the rod or pin 202.

When the members 206 and 201, forming a unit, are slid upon the rods 20I and 202, they can he slid toward the base-member 200 until they strike the collars 203 and 204, and these collars thereby accurately determine the position of the socket laterally of the soundhead, while the rods determine the position and orientation thereof in all other planes.

The outer end of the rod 202 is, as shown, made slightly larger than the remainder thereof, so that the pressure of the spring 208 thereupon tends to maintain the body member 206 firmly against the collar 203. a

The rear portion of the base-member 200 consists of a felt pad 200', which serves to absorb any vibration which might otherwise be imparted to the socket from the mechanism of the sound-' head or projector and produce microphonic noises from the lamp.

The base of the lamp itself is held in the chuck member 209, which is provided with yieldable jaws at its top. The lower portion of the chuck is round and is vertically slidable in a hole in the member 206 in which it fits snugly. Slots 2 l are provided in the chuck jaws, and the pins extending from the sides of the lamp base fit into these slots and prevent rotation of the lamp base in the chuck. A clamping nut 2| l is fitted to the upper portion of the chuck for forcing the jaws inwardly against the lamp base.

The chuck is prevented from rotating in the member 206 by the screw 2l2, which is threaded into the chuck as shown in Fig. 5 and is movable vertically in a slot as shown in Fig. 4. After the chuck has been adjusted to the proper vertical position, it is clamped by tightening the screw 2I2 against the member 206.

Vertical adjustment of the chuck is accomplished by rotation of the nut 2l3. This nut, as shown in Fig. 5, fits into a recess in the member 206 and is held therein as shown in Fig. 4 by the screw 2 l 4 which fits over the collar 2| 5. Since the chuck 209 is threaded to fit the nut 2 l3, it will be apparent that rotation of the vertically-fixed nut will result in vertical movement of the chuck.

Within the chuck at the bottom there is provided an insulating bushing 2l6, within which a contact member 2H is freely slidable, being pressed upwardly by the spring 2 l8 which maintains it firmly in contact with the contact-pin on the bottom of the lamp. A connection strip 219 is attached to the bottom of the contact member 2 I] by a screw 220 and is connected to the spring 208 by a bolt 22!, thereby establishing an electrical circuit to the contact 2 l1 from the rod 202, while the base of the lamp is connected to the rod 20I by the chuck and the body member 206.

A knurled knob 222 is provided by which the body member may be grasped for removal or replacement.

It will be apparent that one or more extra lamps may be adjusted in as many sockets, and if a lamp fails during operation of the apparatus, it requires but an instant to remove the lamp and socket and slide another pre-adjusted lamp into place.

A shield 223 is provided to prevent stray light.

Pad roller assembly The pad roller assemblies are shown in detail in Figs. 6 to 9.

It is necessary that these rollers should definitely maintain the film upon the sprockets, but,

on the other hand, it is undesirable that they should touch the film except when necessary to perform their function. It is accordingly customary to adjust these rollers so that they are spaced from the surface of the sprocket about twice the thickness of the film. There is a possibility that splices may be even thicker than this, and it is therefore necessary to hold the pad rollers not only definitely but yieldably in this position.

It is further necessary that the rollers be instantly releasable for'the purpose of threading the machine; and We accomplish all these results by the construction shown.

The rolleritself is indicated at 259, in Figs. 6 and 7, and is freely rotatable upon a shaft fixed in the movable arm 25I and carrying the knurled knob 252 at its outer end. The arm 25l is pivoted upon the shouldered screw 253, which is fitted into the center plate of the machine, the shoulder 253 fitting against the center plate and establishing proper clearance beneath the head of the screw from free motion of the arm 25l.

The plate 254 lies between the arm 25I and the center plate, and is held against rotation about the screw 253,.which passes through the hole 25'! (Figs. 8 and 9) by the screw 255 which passes through the slot 256. The slot 256 is arcuate in shape, and the plate 254 may be angularly adjusted by a corresponding amount about the screw 253.

As shown in Figs. 8 and 9, both sides of the plate 254 are alike, so that it may be used either right-handed or left-handed, as rendered desirable by the location of surrounding parts.

The extreme limits of motion of the arm 25l are determined by the ends of the arcuate recess 258 into which the round pin 25!! fits, the pin 259 being a force fit in a hole in the arm 25I.

The arm is held at either end ofits travel by the ball 25! and the coil spring 262. The plate 254 is provided with holes 260 into which the coil spring tends to force the ball, but these holes are so located that when the pin 259 is at either end of its travel in the recess 258 the ball 26| .is not quite seated in the corresponding hole, and the arm is thereby held firmly in position.

Since the holding, locating, and adjusting means just described function equally well at either end of the travel of the arm 25 I, either end may be used as the sprocket position; and in addition the plate 254 is reversible as before described.

7 Film stripper Film sometimes has a tendency to cling to the sprocket teeth, and it is accordingly necessary to provide members extending past the teeth to a point adjacent to the surface of the sprocket for stripping the film from the teeth.

I-Ieretofore, the film strippers have usually been formed of several parts secured together by screws. We have found such constructions to be expensive and unreliable, and have accordingly devised the stripper shown in Fig. 10.

A rod 300 is provided, the round end of which is adapted to fit tightly into a hole provided therefor in the center plate of the apparatus. The other end of the rod is cut away as shown at 30! to provide a fiat surface having a width substantially equal to the diameter of the rod.

A plate 302 is provided, and this is cut away at 303 to fit around the'sprocket teeth, the edges 304 being in close proximity to the face of the sprocket.

The plate 302 iSSIJOt-Wldd at 305 to the fiat surface of the rod 300, thereby providing a construction which is not only less expensive than that of the prior art, but which cannot be shaken apart or out of adjustment by vibration or by the impacts of film thereagainst.

Having described the construction and operation of our apparatus and the advantages thereof;

We claim:

1. An exciter lamp socket comprising means for holding the exciter lamp in accurate orientation about its vertical axis, clamping means for rigidly securing the said lamp, and means for adjusting the said clamping means vertically.

2. An exciter lamp socket comprising means for holding the exciter lamp in accurate orienta tion about its vertical axis, clamping means for rigidly securing the said lamp, means for adjusting the said clamping means vertically, and means for securing said clamping means in an adjusted position.

3. Excit'er lamp supporting means for photophonographic apparatus having a center plate, comprising a vibration absorbing pad adapted to be mounted upon said center plate, a base plate supported upon said vibration absorbing pad on the opposite side thereof from the said center plate, and a pair of electrically conducting rods extending perpendicularly from said base plate for supporting a lamp socket.

4. Exciter lamp supporting means for photoph'onographic apparatus having a center plate, comprising a vibration absorbing pad adapted to be mounted upon said center plate, a base plate supported upon said vibration absorbing pad on the opposite side thereof from the said center plate, a pair of electrically conducting rods extending perpendicularly from said base plate, a lamp socket slidable upon said rods, and spring means co acting withone of said rods for maintaining the said socket in operating position.

FRED J. LOOMIS. ELLWOOD W. REYNOLDS. 

